JP2972811B2 - Wood reinforced girder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a timber reinforced girder used for bridges for general forest roads and light roads in mountainous areas.

[0002]

2. Description of the Related Art The softness of wooden bridges has been reconsidered against the background of gentleness to the natural environment. However, due to the increase in the weight of running vehicles and the lack of large-diameter logs, the main girder of wooden bridges is inevitable. It is necessary to rely on glued laminated girder made by laminating small-diameter timber, which is not only economically disadvantageous but also impairs the simplicity of the raw wood and is several times larger than the steel girder which maintains the same strength in terms of weight. I had to endure rationality.

[0003]

In order to solve the above series of absurdities, materials that can be easily procured at the site of mountainous areas, that is, inexpensive thinning materials that are oversupplied, are processed on the spot without being processed. A safe girder must be created that can be used and yet has the strength of a conventional steel girder.

[0004]

In order to solve the above-mentioned problems, a wood-reinforced girder of the present invention uses an even number of thinned lumbers 1 trimmed to the same length and having a thick base and a thin end. Are alternately combined to form a substantially uniform single girder, and both ends of the girder are covered with washers 2, and pillows 10 of the same height are arranged at two symmetrical positions below the middle of the girder. By tightening the turnbuckle 13 inserted between the two pillows 10, the two washers 2 are tensioned by the wire rope 7, so that the thinned material 1 is kept bent.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION
A set of even-numbered and four-thinned thinning materials 1 of the same length and covered with a semi-disc or disk-equipped washer 2 at both ends, with two symmetrical positions in the middle of the thinning materials A pillow material 10 having the same height is arranged, a wire rope 7 is laid over a semi-disc or a disc at the center of the washer, and the wire buckle 13 is fastened with a turnbuckle 13 to give a constant bending, that is, an initial bending to the thinned material. If a load is applied to the upper part of the composite girder, the thinned wood tends to expand. However, if the thinned wood shrinks or the wire rope 7 does not expand, the deformation does not occur. The short-term compressive deformation phenomenon of the thinned wood is negligible because it is extremely small. However, since the wire rope 7 is an elastic body, it elongates and the tensile strength increases, and the deformation of the girder stops at the equilibrium point. It can be understood as a balance point between the load from above and the lifting force (support) of the pillow due to the wire rope tension. If the load further increases, the wire rope 7
The thinned wood will continue to elastically stretch, and the thinned wood will be in a straight line, and if the load increases, it will bend in the opposite direction (downward) beyond the straight line. Since the design is such that the safety limit of the rope is not exceeded, the deflection does not increase beyond the predetermined deflection. Of course, if the initial flexure is taken as large as possible, it can be used as a girder before the linear state (within the range of upward flexure). In the course of long-term use, the wire rope circulatory system may be permanently loosened due to drying shrinkage of wood, etc. Absent.

[0006]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an exploded perspective view of a reinforced girder of the present invention. Thinned timber is a large amount of forest products obtained by thinning and thinning dense forests in the long-term nursery process of building forests, but its value is small because it is thin, easy to bend, and immature. Is one of the biggest problems in the forest industry these days. The present invention relates to a thinned lumber (average diameter of 10 to 18) which is synonymous with the drawback that it is thin and easily bent.
It can be said that it is significant from the viewpoint of developing applications by focusing on the sun. Of course, the tree height of thinned wood is less than ten meters, so it cannot be applied to long girder. However, the span of mountain forest road bridge is usually limited to 6 to 8 meters or less, which can meet general demand. It is.

As shown in FIG. 1, a thinned wood 1 was cut to a fixed length, in this example, a thinned wood having an average diameter of 13 cm was cut to 4 m. A washer 2 capable of fitting the two thinned materials 1 is attached to one set of ends of the thinned materials 1 arranged in parallel, and the washer 2 is formed by welding a metal plate into a box shape. The washer 2 is a bottom plate 3 slightly wider than the width in which the two thinned materials 1 are arranged, and an end plate welded at right angles to the bottom plate 3 having an area covering the kerf surface of the two thinned materials 1. 4, two upper plates 5 welded at right angles to the end plate 4 at intervals of wire ropes 7 with the width of the thinned wood 1 on the opposite side of the bottom plate 3, and the upper plate 5 and the bottom plate 3 And two trapezoidal side plates 6 welded so as to cover the side surfaces of the thinned material 1. Further, a semi-disc 8 having a thickness to be engaged with a wire rope 7 passing through a portion located between the upper plates 5 is welded to an end plate 4 of the washer 2 in a central vertical direction. A rope groove 9 for fitting the wire rope 7 is formed on a circumferential end surface of the wire 8. The bottom plate 3 of the washer 2 can be appropriately changed in design so as not to contact the wire rope 7.

As shown in FIG. 2, the height of the thinned wood 1 is 3 at two places 1/3 and 2/3 from one end.
A pillow material 10 having a diameter of 0 to 40 cm and a diameter of 25 cm is arranged.
The upper surface is evenly straddled over two thinned materials 1, and the lower surface is covered with a receiving member 12 with a rope guide 11. Then, one wire rope 7 (diameter 12.5 mm, elastic modulus 10,000)
kg / mm, structural strand rope with a breaking load of 11.5 ton) 7 is stretched endlessly, and the end of the wire rope is
The turnbuckle 13 located between the pillows 10 was tightened by hooking the hook 14 of the turnbuckle 13 via the locking ring 20 to give the thinned material a deflection of 1% (4 cm). In addition,
The pillow material only flexed and was always sufficiently fixed by the tension of the strong wire rope.

Next, the experiment on the wood-reinforced girder of the present invention will be described. The experiment was conducted using a large-scale strength tester, and the relationship between load and bending deformation (strain) was reduced to -1%. Until it was measured. Note that this initial deflection of 1% is sufficiently lower than the allowable bending stress of thinned wood of 200 kg / cm 2 and has a sufficient amount of deflection. The results of the test were fairly close to the theoretical values, confirming the "load-bearing effect" inherent to this reinforced girder. In addition, as a result of the additional test, even when the initial bending of 2% was actually given, the thinned wood was sound and its softness was confirmed again.

From the above test results, the validity of the theoretical estimation of the reinforced girder was obtained, so that the wire rope was changed in tension and the wire rope 7 was separated at both ends as shown in FIGS. Next, an improved system in which each is doubled was considered.
As the washer 2, a disk 15 is used instead of the semi-disk 8.
A rope groove 9 is formed on the entire circumferential end face of the cable. Also,
As shown in FIG. 4, the receiving member 12 includes a guide plate 16 welded to the bottom surface to guide the wire rope 7 from left and right,
As shown in FIG. 5, a wire rope 7 is hung from above and below on a disk 15 to reinforce the guide plate 16 and, as shown in FIG. And lock it.

From the above experimental results, it is presumed that this method is more advantageous because the load supporting force of the wire rope is doubled according to this method. For example, when the span is 6 m, the design load is 8 tons, and the average diameter of the thinned wood is 13 cm, the initial deflection amount is 1% when a pillow material having a height of 30 cm, a structural strand rope having a diameter of 20 mm and a breaking strength of 28.5 tons is used. Then,
It has been calculated that it is possible to respond within a deflection range of -1%, and that the safety factor of the wire rope, the compression of the thinned wood, the bending under load, and the safety against buckling are all within acceptable ranges. When this is replaced with a steel girder I-beam under the same load condition, it is necessary to introduce a material that increases by 14% in weight of the thinned wood reinforcement girder. However, it can be expected as a product of hybrid. Similarly, compared to a lumber girder made of wood, it is necessary to increase the weight of glued lumber by about four times.

In the conventional rigid girder, the bending limit is suppressed to 1/300 of the span even in the case of a wooden bridge, but this is mainly due to the regulation from the influence of vibration. On the other hand, in the case of the thinning wood reinforcement girder, though it exceeds three times,
It is a girder of a hybrid structure and the basic conditions are different. This is not a problem in practical use because the wire rope under high tension absorbs vibration and the vehicle traveling speed on the forest road is low. The above calculation is based on the assumption that the vehicle has a design load of 20 tons according to the forest road regulations. However, of course, it is possible to reduce the scale and design a light road.
The applications are expected to expand further.

[0013]

According to the conventional girder, the rigidity is the life, and only the enhancement of the rigidity is the proposition, and it has been a common sense to minimize the deformation of the girder. However, if a flexible material that is easy to bend is not used, there is no turn of the wire rope that tries to back up, and the hybrid effect is
Some of them exceed conventional rigid girder, and "softly control rigidity"
The effect is born. Moreover, this wood reinforced girder is
It has a simple structure and is easy to crosslink, and it is easy to procure log materials in the field. It is very economical, and the development of surplus thinning wood applications is significant. Of course, wood has the disadvantage of decay, but it is easy to replace, so it is only necessary to periodically renew it every few years. In addition, it can be said that the strength can be controlled by retightening the turnbuckle during use, which is a feature that cannot be obtained with the conventional rigid girder. With the development of this wood reinforced girder, floor slabs,
By using thinned timber on the balustrade, it is expected that in the future, the number of forest road bridges that match the natural environment of the mountainous area and will be more scenic, and that harmony between forestry and national recreation will be enhanced.

[Brief description of the drawings]

FIG. 1 is a perspective view of a wood-reinforced girder of the present invention.

FIG. 2 is an explanatory view of a wood-reinforced girder of the present invention.

FIG. 3 is a partial side view of another wood-reinforced girder of the present invention.

FIG. 4 is a front view of a receiving member of another wood-reinforced girder of the present invention.

FIG. 5 is a sectional view taken along the arrow line AA in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Thinning material 2 Washer 3 Bottom plate 4 End plate 5 Top plate 6 Side plate 7 Wire rope 8 Semi disk 9 Rope groove 10 Pillow material 11 Rope guide 12 Receiving member 13 Turnbuckle 14 Hook 15 Disk 16 Guide plate 17 Triangular plate 18 Arc plate 19 Wood piece 20 Lock ring

────────────────────────────────────────────────── ─── Continuation of the front page (56) References Japanese Utility Model Showa 48-64216 (JP, U) Registered Utility Model 3015392 (JP, U) Patent 2688631 (JP, B2) Patent 2687995 (JP, B2) -53771 (JP, Y2) JP 31-9148 (JP, B1) JP 48-7141 (JP, Y1) JP 48-24656 (JP, Y1) JP 48-32963 (JP, Y1) (58) Fields surveyed (Int. Cl. ⁶ , DB name) E04C 3/18

Claims (1)

(57) [Claims] 1. An even number of thinned wood pieces trimmed to the same length are knitted into a substantially uniform single girder by alternately combining a thick base opening and a thin end opening. Put a washer,
Pillows of the same height are placed at two symmetrical positions below the middle of the girder, and the turnbuckle inserted between both pillows is tightened,
A timber reinforced girder characterized by tensioning the washer between both washers with a wire rope to keep the thinned wood flexible.